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Underlying Causes

POTS often co-occurs with Ehlers-Danlos Syndrome and mast cell activation syndrome.

It is important to look for possible underlying causes of postural orthostatic tachycardia syndrome (POTS).  Finding and treating those medical problems can allow better management of POTS symptoms. 

Common Comorbidities with POTS

Ehlers-Danlos Syndrome (EDS)

Eighty percent of people with Ehlers-Danlos Syndrome have POTS (but not the other way around).  Most people with POTS have Type III EDS which is the hypermobility type.  There is currently no known gene for this type of EDS, so diagnosis is made using family history and clinical evaluation. To meet the criteria for EDS Type III, patients must meet at least one of the major diagnostic criteria and two minor criteria.

Major Diagnostic Criteria for the Hypermobility Type of EDS
  • Joint hypermobility, which usually is confirmed by a score of five or more on the nine-point Beighton scale including:
            -One point for bending the pinkie finger backwards beyond 90º
            -One point for pulling the thumb to the forearm
            -One point for hyperextension of each elbow >10º
            -One point for hyperextension of each knee >10º
            -One point for placing the palms on the floor with the knees fully extended
  • Soft or velvety skin with normal or slightly increased extensibility.  A skin flap greater than 1.5 cm indicates increased extensibility.
  • Absence of skin or soft tissue fragility, which is suggestive of other types of EDS.
  • Molluscoid pseudotumors
  • Surgical complications, such as incisional hernia, wound splitting, or sutures tearing through tissues and failing to hold.
 Minor Diagnostic Criteria for the Hypermobility Type of EDS
  • Family history of similar features without significant skin or soft tissue fragility in a pattern consistent with autosomal dominant inheritance
  • Recurrent joint dislocations or subluxations
  • Chronic joint or limb pain
  • Easy bruising
  • Functional bowel disorders (functional gastritis, irritable bowel syndrome)
  • Neurally mediated hypotension or postural orthostatic tachycardia
  • High, narrow palate
  • Dental crowding

If you are interested in Ehlers-Danlos Syndrome, please check out this page from the National Institutes of Health.

Mast Cell Activation Syndrome (MCAS)

Mast cell activation syndrome (MCAS) is also commonly associated with POTS and can present in a wide variety of ways.  Mast cells are normally found throughout the body, and are most famous for their role in allergy and inflammation.  In the case of mast cell activation syndrome, the mast cells are frequently releasing too much histamine. Symptoms of mast cell activation syndrome include:

  • Recurrent abdominal pain
  • Flushing
  • Itching
  • Nasal congestion
  • Coughing
  • Chest tightness
  • Wheezing
  • Lightheadedness
  • Diarrhea

Blood and urine tests can be run to confirm this diagnosis including blood tryptase levels and N-methyl histamine and  prostaglandin D2 among others in a 24 hour urine sample.  Allergists or immunologists are most likely to understand, diagnose, and treat MCAS.

Perhaps most importantly, people with mast cell activation syndrome will see an improvement in the above symptoms when they take a combination of Histamine-1 (Zyrtec, Benedryl) and Histamine-2 (Pepcid-AC) antagonists.  Talk with your doctor about trying this regimen for a week to see if your symptoms improve.

Click here for scientific articles about mast cell activation syndrome.

Other Possible Underlying Causes of POTS

Here is a list of some common underlying causes for POTS.